Hydraulic power systems utilize hydraulic pressure for controlling power units. Such systems generally include a pressure switch to provide an electrical signal indicating that a preset pressure has been achieved. When the pressure switch is connected to a fluid pipeline system, often there will be a rapid rise in pressure within the system, which can result in pressure surge, fluid hammer and pressure pulsation. Pressure surge is essentially the result of a wave generated when a fluid in motion is forced to stop or change direction suddenly (e.g., momentum change). Fluid hammer generates a very loud banging, knocking or hammering noise in the pipes that occurs when the flow is suddenly terminated. Fluid hammer may occur as a result of a pressure wave or a shock wave that travels faster than the speed of sound through the pipes and which is brought on by a sudden cessation in the velocity of the fluid, or a change in the fluid direction.
Fluid hammer commonly occurs when a valve is closed suddenly at the end of the pipeline system and a pressure wave propagates in the pipe. Fluid hammer can also occur due to several factors such as, for example, improperly sized piping in relation to fluid flow velocity, high fluid pressure with no pressure-reducing valve, straight runs that are too long without bends, and the lack of a dampening system in place to reduce or absorb shockwaves. Such pressure pulsations and fluid hammer present in hydraulic systems can cause serious problems regarding safety and switch reliability. Such surge phenomenon may result in fatigue and catastrophic switch failure.
Pressure snubbers are widely utilized for dampening, filtering and/or maintaining a steady flow of media. A pressure snubber is a mechanical device that limits pressure or velocity surges on measurement devices. Such pressure snubbers can be connected between the process and the measurement device allowing a relatively slow change in pressure or velocity to limit damage to the hardware. Such devices are common in industrial environments.
The majority of prior art snubbers possess a porous metal disc as a snubbing element available in three standard grades of porosity. Due to the large filter surface, such snubber has fewer tendencies to clog than an orifice type device. Additionally, the internal parts associated with the pressure switch need to be designed according to size of the snubber. Such prior art snubbers, however, require an additional adaptor, which increases the switch length and may be troublesome. Furthermore, the cost for packaging such snubbers may increase, which can lead to further enlarge the size of the final switch assembly and the complexity of the system, thereby resulting in reduced reliability.
Based on foregoing, it is believed that a need exists for an improved hydraulic pressure switch apparatus for controlling the operation of hydraulic pressure pumps. A need also exists for an improved snubbing element for dampening and filtration purposes, as described in greater detail herein.